The present invention relates to apparatus and methods for inserting an intraocular lens (IOL) through a small incision into an eye. More particularly, the invention relates to such apparatus and methods for first multiply folding an IOL to attain a reduced insertion profile and then inserting the lens through an incision in the eye.
An intraocular lens (IOL) is implanted in the eye, for example, as a replacement for the natural crystalline lens after cataract surgery or to alter the optical properties of (provide vision correction to) an eye in which the natural lens remains. IOLs often include an optic, and preferably at least one (and normally two) flexible fixation member or haptic, which extends from the optic and becomes affixed in the eye to secure the lens in position. The optic normally includes an optically clear lens.
The IOL preferably is implanted directly into the eye through a small incision formed in the ocular tissue of the eye. Making the incision as small as possible reduces trauma and speeds healing. To fit through this small incision, optics of modern IOLs are designed to be deformed, e.g., folded, rolled or the like, to a relatively small insertion profile and then allowed to substantially return to their original shape within the eye. To permit folding (deforming) so that the IOL can be inserted into the eye through a small incision, the optic may be made of silicone polymeric material, flexible or foldable acrylic polymeric material, and the like.
A very useful technique for inserting an IOL into the eye includes the use of an IOL injector or cartridge, such as the IOL injector described in Bartell, U.S. Pat. No. 4,681,102. These IOL injectors include a load chamber which is connected to an injection tube. The load chamber includes a lumen for receiving the IOL and is hinged so that the side walls thereof can be opened like a book. Closure of this lumen folds the IOL and maintains the IOL in a folded state. The injection tube includes a small diameter distal tip which is insertable into the incision within the eye. The IOL is transferable from the load chamber through the injection tube and into the eye. These IOL injectors simplify the placement of the IOL within the eye and reduce chances of surgeon error.
In these generally accepted apparatuses, the insertion cartridge is held in a handpiece having a plunger rod longitudinally displaceable therewithin. The plunger rod moves distally to urge the IOL from the load chamber through the injection tube and into the eye. Zaleski U.S. Pat. No. 5,643,276 discloses an IOL insertion apparatus in which the rod is rotated relative to the handpiece being held by the surgeon The rod, in turn, contacts the IOL and provides the IOL in the desired orientation for insertion into the eye. The disclosure of this patent is incorporated in its entirety herein by reference.
Many prior art cartridges singly fold the IOL into a rolled or U-shaped configuration. That is, two diametrically opposite side edges of the optic are folded toward one another into close or overlapping proximity. This rolled configuration reduces the insertion profile at least in one dimension from the optic diameter to about one half the optic diameter. Most currently available IOLs have a minimum diameter on the order of 6 mm and a minimum thickness of 1 mm to 2 mm. Most practical intraocular lens implantation procedures thus require an incision in the eye that is greater than 3-4 mm, to also accommodate the injection tube. It would be advantageous to provide IOL insertion apparatus and methods which reduce the insertion profile of a folded IOL in the apparatus, thus facilitating insertion of the IOL through a small incision in the eye and reducing trauma to the patient.
In addition, the IOL is inserted and unfolds in the anterior chamber of the eye to generally assume its final orientation. To accomplish this using a conventional U-shaped fold configuration, the IOL is maneuvered into an orientation in which the opposite side edges are posteriorly directed (to the rear), while the convex midportion of the optic is anteriorly directed (to the front). When released from the injection tube, therefore, the convex face of the optic is facing in the anterior direction, parallel and spaced from the cornea. To enable this desirable insertion/unfolding step, the space required in the anterior-posterior direction within the eye is on the order of 3 mm (about half the diameter of the optic). It would be desirably to be able to reduce the space necessary for the unfolding step, to help avoid contacting the IOL with surrounding anatomical structures.
An apparatus for further reducing the insertion profile of an IOL from the conventional U-shape can be seen in Brady, U.S. Pat. No. 5,702,402. In that patent, forceps manipulated in conjunction with a tubular member form a xe2x80x9cWxe2x80x9d configuration in an IOL with multiple folds, as seen for example, in FIGS. 2B and 10. McDonald, et al., U.S. Pat. No. 5,711,317, and McDonald, U.S. Pat. No. 5,919,197 both disclose folding of an IOL into an xe2x80x9cMxe2x80x9d shape (the same as the xe2x80x9cWxe2x80x9d shape) to reduce the insertion profile. The folding is carried out with a relatively complex five-fingered wire element. There is a need for a simpler and more reliable way to multiply fold IOLs to produce a smaller insertion profile.
The present invention provides an improved apparatus for inserting an intraocular lens through an incision into an eye. The apparatus operates in an environment that is similar to existing systems, with a cartridge being loaded into a handpiece, and plunger rod of the handpiece extending through a lumen in the cartridge to push an intraocular lens from an injection tube of the cartridge through an incision in the eye.
In one aspect, the present invention provides a system for multiply folding an intraocular lens having an optic prior to insertion of the lens in an eye. The system includes an insertion cartridge for receiving the intraocular lens in a singly folded configuration, and a folding member sized to pass through an aperture in the cartridge and multiply fold the lens. The insertion cartridge includes a generally cylindrical proximal loading chamber defining an axis and sized to receive the lens in its singly folded configuration with the optic being curved in a first direction and generally conforming to an inner wall of the chamber. Upon passage through the aperture in the cartridge, the folding member contacts a midportion of the optic and displaces it away from the inner wall, curving the optic in a second direction opposite the first direction.
The folding member may be formed separately or as part of the cartridge. If part of the cartridge, the folding member may be pivotally connected thereto so as to move radially with respect to the aperture. Locking structure may be provided to retain the folding member in its radially inward position. The aperture preferably comprises a closed-ended axial slot and a folding member is desirably axially elongate so as to fit and be guided through the slot and contact the optic generally along an axial line. The folding member may include a stop portion size larger than the aperture to limit the insertion depth of the folding member. The system may further include a handpiece for receiving the cartridge including a pusher rod for displacing the intraocular lens from within the cartridge into an eye. The folding member may therefore be formed as part of the handpiece, such as a fixed axial rib extending inward from an inner wall of a handpiece chamber that aligns with and extends through the axial slot in the cartridge.
In a further aspect of the present invention, an insertion cartridge for receiving and folding an intraocular lens having an optic comprises a generally cylindrical loading chamber defined by two arcuate walls. The arcuate walls are convertible between a closed relationship defining the loading chamber and an open relationship exposing the inner concave surfaces of the walls. An intraocular lens may be placed on the concave surfaces in the open relationship and may be singly folded by conversion of the arcuate walls to the closed relationship. The cartridge further includes an injection lumen contiguous with the loading chamber and extending distally therefrom. A closed-ended axial slot defined in the cartridge opens to the loading chamber in a location adjacent a midportion of the optic of the singly folded intraocular lens. The slot is sized to receive and axially elongate folding member therethrough that contacts and displaces the midportion of the optic radially inward, thereby multiply folding the intraocular lens into an xe2x80x9cMxe2x80x9d or xe2x80x9cWxe2x80x9d shape. The closed-ended axial slot of the cartridge may be located between the two arcuate walls, either at the hinge, or opposite the hinge between two free edges of the walls. A pair of folding wings may extend radially outward from the free edges of the arcuate walls, and the slot may be defined by facing recesses in the folding wings.
In another aspect of the present invention, a method of multiply folding an intraocular lens having an optic prior to insertion of the lens in an eye comprises the steps of placing the lens in a generally cylindrical loading chamber of cartridge, and inserting a folding member through an aperture in the cartridge. The lens is placed in the loading chamber such that the optic generally conforms to an inner wall of the cylindrical chamber and is singly curved in a first direction. The folding member contacts a midportion of the optic of the lens and displaces it away from inner wall, thus curving the optic in a second direction opposite first so that the lens is multiply folded within the loading chamber. The method may include providing a folding member separate from the cartridge, the folding member including a planar portion and a stop portion for limiting insertion of the planar portion through the aperture. Alternatively, a handpiece may be provided into which the cartridge is mounted, wherein the folding member is formed on the handpiece and inserts automatically through the aperture when the cartridge is mounted on the handpiece. The folding member may be fixed or movable on the handpiece. Still further, the folding member may be movably connected to the cartridge and displacing inward upon mounting of the cartridge on handpiece.
These and other aspects of the present invention will become apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.